pip broken, reinstall doesn't work. EC2

Question

I am using pip on EC2 now, python version is 2.7. 'sudo pip' suddenly doesn't work anymore.

[ec2-user@ip-172-31-17-194 ~]$ sudo pip install validate_email
Traceback (most recent call last):
  File "/usr/bin/pip", line 5, in <module>
    from pkg_resources import load_entry_point
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3138, in <module>
    @_call_aside
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3124, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3151, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 663, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 676, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 849, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pip==6.1.1' distribution was not found and is required by the application
[ec2-user@ip-172-31-17-194 ~]$ which pip
/usr/local/bin/pip

Answer 1

first, which pip is not going to return the same result as sudo which pip, so you should check that out first.

you may also consider not running pip as sudo at all. Is it acceptable & safe to run pip install under sudo?

second, can you try this:

easy_install --upgrade pip

if you get an error here (regarding pip's wheel support), try this, then run the above command again:

easy_install -U setuptools

Answer 2

I fixed the same error ("The 'pip==6.1.1' distribution was not found") by using the tip of Wesm :

$> which pip && sudo which pip
/usr/local/bin/pip
/usr/bin/pip

So, it seels that "pip" of average user and of root are not the same. Will fix it later.

Then I ran "sudo easy_install --upgrade pip" => succeed

Then I used "sudo /usr/local/bin/pip install " and it works.